Intermittent failure for screenshot tests due to window sizes

[samtygier-stfc]

Summary

We are currently seeing a large number of failures of the screenshot tests because the Spectrum window is mostly rendering at a different size than it was last week.

There are no obvious code or package changes that should cause this.

Widget sizing in Qt is complicated. Things may change size as various bits of a window are initialised or data is loaded. But the tests ought to do things in a consistent way, and give a consistent result.

Steps To Reproduce

Happening to most current PRs

Expected Behaviour

Windows render at a consistent size.

Current Behaviour

Spectrum window is rendering at a different size than it was last week.

Context

Current main

[samtygier-stfc]

Git bisect suggests it could have been:

Bisecting: 0 revisions left to test after this (roughly 0 steps)
[cda8ff90f61d96c45bcba4805c207e9a0b2b205d] The main window is not the parent of SpectrumProjectionWidget

Change is in #2356

It was noted in the comments, but the baseline branch did not get merged on applitools when the PR was merged.